<?php
/**
 * Parsedown class
 * Parse MarkDown
 *
 * @since 2.9
 *
 * @package RosarioSIS
 * @subpackage classes
 */

/**
 * ParseDown class
 *
 * @todo add Markdown editor (full screen!)? https://jbt.github.io/markdown-editor/
 *
 * @link http://parsedown.org
 *
 * @copyright (c) Emanuil Rusev http://erusev.com
 *
 * @license MIT https://github.com/erusev/parsedown/blob/master/LICENSE.txt
 */
class Parsedown
{
	# ~

	const version = '1.7.4';

	# ~

	function text($text)
	{
		# make sure no definitions are set
		$this->DefinitionData = array();

		# standardize line breaks
		$text = str_replace(array("\r\n", "\r"), "\n", $text);

		# remove surrounding line breaks
		$text = trim($text, "\n");

		# split text into lines
		$lines = explode("\n", $text);

		# iterate through lines to identify blocks
		$markup = $this->lines($lines);

		# trim line breaks
		$markup = trim($markup, "\n");

		return $markup;
	}

	#
	# Setters
	#

	function setBreaksEnabled($breaksEnabled)
	{
		$this->breaksEnabled = $breaksEnabled;

		return $this;
	}

	protected $breaksEnabled;

	function setMarkupEscaped($markupEscaped)
	{
		$this->markupEscaped = $markupEscaped;

		return $this;
	}

	protected $markupEscaped;

	function setUrlsLinked($urlsLinked)
	{
		$this->urlsLinked = $urlsLinked;

		return $this;
	}

	protected $urlsLinked = true;

	function setSafeMode($safeMode)
	{
		$this->safeMode = (bool) $safeMode;

		return $this;
	}

	protected $safeMode;

	protected $safeLinksWhitelist = array(
		'http://',
		'https://',
		'ftp://',
		'ftps://',
		'mailto:',
		'data:image/png;base64,',
		'data:image/gif;base64,',
		'data:image/jpeg;base64,',
		'irc:',
		'ircs:',
		'git:',
		'ssh:',
		'news:',
		'steam:',
	);

	#
	# Lines
	#

	protected $BlockTypes = array(
		'#' => array('Header'),
		'*' => array('Rule', 'List'),
		'+' => array('List'),
		'-' => array('SetextHeader', 'Table', 'Rule', 'List'),
		'0' => array('List'),
		'1' => array('List'),
		'2' => array('List'),
		'3' => array('List'),
		'4' => array('List'),
		'5' => array('List'),
		'6' => array('List'),
		'7' => array('List'),
		'8' => array('List'),
		'9' => array('List'),
		':' => array('Table'),
		'<' => array('Comment', 'Markup'),
		'=' => array('SetextHeader'),
		'>' => array('Quote'),
		'[' => array('Reference'),
		'_' => array('Rule'),
		'`' => array('FencedCode'),
		'|' => array('Table'),
		'~' => array('FencedCode'),
	);

	# ~

	protected $unmarkedBlockTypes = array(
		'Code',
	);

	#
	# Blocks
	#

	protected function lines(array $lines)
	{
		$CurrentBlock = null;

		foreach ($lines as $line)
		{
			if (chop($line) === '')
			{
				if (isset($CurrentBlock))
				{
					$CurrentBlock['interrupted'] = true;
				}

				continue;
			}

			if (strpos($line, "\t") !== false)
			{
				$parts = explode("\t", $line);

				$line = $parts[0];

				unset($parts[0]);

				foreach ($parts as $part)
				{
					$shortage = 4 - mb_strlen($line, 'utf-8') % 4;

					$line .= str_repeat(' ', $shortage);
					$line .= $part;
				}
			}

			$indent = 0;

			while (isset($line[$indent]) and $line[$indent] === ' ')
			{
				$indent ++;
			}

			$text = $indent > 0 ? substr($line, $indent) : $line;

			# ~

			$Line = array('body' => $line, 'indent' => $indent, 'text' => $text);

			# ~

			if (isset($CurrentBlock['continuable']))
			{
				$Block = $this->{'block'.$CurrentBlock['type'].'Continue'}($Line, $CurrentBlock);

				if (isset($Block))
				{
					$CurrentBlock = $Block;

					continue;
				}
				else
				{
					if ($this->isBlockCompletable($CurrentBlock['type']))
					{
						$CurrentBlock = $this->{'block'.$CurrentBlock['type'].'Complete'}($CurrentBlock);
					}
				}
			}

			# ~

			$marker = $text[0];

			# ~

			$blockTypes = $this->unmarkedBlockTypes;

			if (isset($this->BlockTypes[$marker]))
			{
				foreach ($this->BlockTypes[$marker] as $blockType)
				{
					$blockTypes []= $blockType;
				}
			}

			#
			# ~

			foreach ($blockTypes as $blockType)
			{
				$Block = $this->{'block'.$blockType}($Line, $CurrentBlock);

				if (isset($Block))
				{
					$Block['type'] = $blockType;

					if ( ! isset($Block['identified']))
					{
						$Blocks []= $CurrentBlock;

						$Block['identified'] = true;
					}

					if ($this->isBlockContinuable($blockType))
					{
						$Block['continuable'] = true;
					}

					$CurrentBlock = $Block;

					continue 2;
				}
			}

			# ~

			if (isset($CurrentBlock) and ! isset($CurrentBlock['type']) and ! isset($CurrentBlock['interrupted']))
			{
				$CurrentBlock['element']['text'] .= "\n".$text;
			}
			else
			{
				$Blocks []= $CurrentBlock;

				$CurrentBlock = $this->paragraph($Line);

				$CurrentBlock['identified'] = true;
			}
		}

		# ~

		if (isset($CurrentBlock['continuable']) and $this->isBlockCompletable($CurrentBlock['type']))
		{
			$CurrentBlock = $this->{'block'.$CurrentBlock['type'].'Complete'}($CurrentBlock);
		}

		# ~

		$Blocks []= $CurrentBlock;

		unset($Blocks[0]);

		# ~

		$markup = '';

		foreach ($Blocks as $Block)
		{
			if (isset($Block['hidden']))
			{
				continue;
			}

			$markup .= "\n";
			$markup .= isset($Block['markup']) ? $Block['markup'] : $this->element($Block['element']);
		}

		$markup .= "\n";

		# ~

		return $markup;
	}

	protected function isBlockContinuable($Type)
	{
		return method_exists($this, 'block'.$Type.'Continue');
	}

	protected function isBlockCompletable($Type)
	{
		return method_exists($this, 'block'.$Type.'Complete');
	}

	#
	# Code

	protected function blockCode($Line, $Block = null)
	{
		if (isset($Block) and ! isset($Block['type']) and ! isset($Block['interrupted']))
		{
			return;
		}

		if ($Line['indent'] >= 4)
		{
			$text = substr($Line['body'], 4);

			$Block = array(
				'element' => array(
					'name' => 'pre',
					'handler' => 'element',
					'text' => array(
						'name' => 'code',
						'text' => $text,
					),
				),
			);

			return $Block;
		}
	}

	protected function blockCodeContinue($Line, $Block)
	{
		if ($Line['indent'] >= 4)
		{
			if (isset($Block['interrupted']))
			{
				$Block['element']['text']['text'] .= "\n";

				unset($Block['interrupted']);
			}

			$Block['element']['text']['text'] .= "\n";

			$text = substr($Line['body'], 4);

			$Block['element']['text']['text'] .= $text;

			return $Block;
		}
	}

	protected function blockCodeComplete($Block)
	{
		$text = $Block['element']['text']['text'];

		$Block['element']['text']['text'] = $text;

		return $Block;
	}

	#
	# Comment

	protected function blockComment($Line)
	{
		if ($this->markupEscaped or $this->safeMode)
		{
			return;
		}

		if (isset($Line['text'][3]) and $Line['text'][3] === '-' and $Line['text'][2] === '-' and $Line['text'][1] === '!')
		{
			$Block = array(
				'markup' => $Line['body'],
			);

			if (preg_match('/-->$/', $Line['text']))
			{
				$Block['closed'] = true;
			}

			return $Block;
		}
	}

	protected function blockCommentContinue($Line, array $Block)
	{
		if (isset($Block['closed']))
		{
			return;
		}

		$Block['markup'] .= "\n" . $Line['body'];

		if (preg_match('/-->$/', $Line['text']))
		{
			$Block['closed'] = true;
		}

		return $Block;
	}

	#
	# Fenced Code

	protected function blockFencedCode($Line)
	{
		if (preg_match('/^['.$Line['text'][0].']{3,}[ ]*([^`]+)?[ ]*$/', $Line['text'], $matches))
		{
			$Element = array(
				'name' => 'code',
				'text' => '',
			);

			if (isset($matches[1]))
			{
				/**
				 * https://www.w3.org/TR/2011/WD-html5-20110525/elements.html#classes
				 * Every HTML element may have a class attribute specified.
				 * The attribute, if specified, must have a value that is a set
				 * of space-separated tokens representing the various classes
				 * that the element belongs to.
				 * [...]
				 * The space characters, for the purposes of this specification,
				 * are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab),
				 * U+000A LINE FEED (LF), U+000C FORM FEED (FF), and
				 * U+000D CARRIAGE RETURN (CR).
				 */
				$language = substr($matches[1], 0, strcspn($matches[1], " \t\n\f\r"));

				$class = 'language-'.$language;

				$Element['attributes'] = array(
					'class' => $class,
				);
			}

			$Block = array(
				'char' => $Line['text'][0],
				'element' => array(
					'name' => 'pre',
					'handler' => 'element',
					'text' => $Element,
				),
			);

			return $Block;
		}
	}

	protected function blockFencedCodeContinue($Line, $Block)
	{
		if (isset($Block['complete']))
		{
			return;
		}

		if (isset($Block['interrupted']))
		{
			$Block['element']['text']['text'] .= "\n";

			unset($Block['interrupted']);
		}

		if (preg_match('/^'.$Block['char'].'{3,}[ ]*$/', $Line['text']))
		{
			$Block['element']['text']['text'] = substr($Block['element']['text']['text'], 1);

			$Block['complete'] = true;

			return $Block;
		}

		$Block['element']['text']['text'] .= "\n".$Line['body'];

		return $Block;
	}

	protected function blockFencedCodeComplete($Block)
	{
		$text = $Block['element']['text']['text'];

		$Block['element']['text']['text'] = $text;

		return $Block;
	}

	#
	# Header

	protected function blockHeader($Line)
	{
		if (isset($Line['text'][1]))
		{
			$level = 1;

			while (isset($Line['text'][$level]) and $Line['text'][$level] === '#')
			{
				$level ++;
			}

			if ($level > 6)
			{
				return;
			}

			$text = trim($Line['text'], '# ');

			$Block = array(
				'element' => array(
					'name' => 'h' . min(6, $level),
					'text' => $text,
					'handler' => 'line',
				),
			);

			return $Block;
		}
	}

	#
	# List

	protected function blockList($Line)
	{
		list($name, $pattern) = $Line['text'][0] <= '-' ? array('ul', '[*+-]') : array('ol', '[0-9]+[.]');

		if (preg_match('/^('.$pattern.'[ ]+)(.*)/', $Line['text'], $matches))
		{
			$Block = array(
				'indent' => $Line['indent'],
				'pattern' => $pattern,
				'element' => array(
					'name' => $name,
					'handler' => 'elements',
				),
			);

			if($name === 'ol')
			{
				$listStart = stristr($matches[0], '.', true);

				if($listStart !== '1')
				{
					$Block['element']['attributes'] = array('start' => $listStart);
				}
			}

			$Block['li'] = array(
				'name' => 'li',
				'handler' => 'li',
				'text' => array(
					$matches[2],
				),
			);

			$Block['element']['text'] []= & $Block['li'];

			return $Block;
		}
	}

	protected function blockListContinue($Line, array $Block)
	{
		if ($Block['indent'] === $Line['indent'] and preg_match('/^'.$Block['pattern'].'(?:[ ]+(.*)|$)/', $Line['text'], $matches))
		{
			if (isset($Block['interrupted']))
			{
				$Block['li']['text'] []= '';

				$Block['loose'] = true;

				unset($Block['interrupted']);
			}

			unset($Block['li']);

			$text = isset($matches[1]) ? $matches[1] : '';

			$Block['li'] = array(
				'name' => 'li',
				'handler' => 'li',
				'text' => array(
					$text,
				),
			);

			$Block['element']['text'] []= & $Block['li'];

			return $Block;
		}

		if ($Line['text'][0] === '[' and $this->blockReference($Line))
		{
			return $Block;
		}

		if ( ! isset($Block['interrupted']))
		{
			$text = preg_replace('/^[ ]{0,4}/', '', $Line['body']);

			$Block['li']['text'] []= $text;

			return $Block;
		}

		if ($Line['indent'] > 0)
		{
			$Block['li']['text'] []= '';

			$text = preg_replace('/^[ ]{0,4}/', '', $Line['body']);

			$Block['li']['text'] []= $text;

			unset($Block['interrupted']);

			return $Block;
		}
	}

	protected function blockListComplete(array $Block)
	{
		if (isset($Block['loose']))
		{
			foreach ($Block['element']['text'] as &$li)
			{
				if (end($li['text']) !== '')
				{
					$li['text'] []= '';
				}
			}
		}

		return $Block;
	}

	#
	# Quote

	protected function blockQuote($Line)
	{
		if (preg_match('/^>[ ]?(.*)/', $Line['text'], $matches))
		{
			$Block = array(
				'element' => array(
					'name' => 'blockquote',
					'handler' => 'lines',
					'text' => (array) $matches[1],
				),
			);

			return $Block;
		}
	}

	protected function blockQuoteContinue($Line, array $Block)
	{
		if ($Line['text'][0] === '>' and preg_match('/^>[ ]?(.*)/', $Line['text'], $matches))
		{
			if (isset($Block['interrupted']))
			{
				$Block['element']['text'] []= '';

				unset($Block['interrupted']);
			}

			$Block['element']['text'] []= $matches[1];

			return $Block;
		}

		if ( ! isset($Block['interrupted']))
		{
			$Block['element']['text'] []= $Line['text'];

			return $Block;
		}
	}

	#
	# Rule

	protected function blockRule($Line)
	{
		if (preg_match('/^(['.$Line['text'][0].'])([ ]*\1){2,}[ ]*$/', $Line['text']))
		{
			$Block = array(
				'element' => array(
					'name' => 'hr'
				),
			);

			return $Block;
		}
	}

	#
	# Setext

	protected function blockSetextHeader($Line, array $Block = null)
	{
		if ( ! isset($Block) or isset($Block['type']) or isset($Block['interrupted']))
		{
			return;
		}

		if (chop($Line['text'], $Line['text'][0]) === '')
		{
			$Block['element']['name'] = $Line['text'][0] === '=' ? 'h1' : 'h2';

			return $Block;
		}
	}

	#
	# Markup

	protected function blockMarkup($Line)
	{
		if ($this->markupEscaped or $this->safeMode)
		{
			return;
		}

		if (preg_match('/^<(\w[\w-]*)(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*(\/)?>/', $Line['text'], $matches))
		{
			$element = strtolower($matches[1]);

			if (in_array($element, $this->textLevelElements))
			{
				return;
			}

			$Block = array(
				'name' => $matches[1],
				'depth' => 0,
				'markup' => $Line['text'],
			);

			$length = strlen($matches[0]);

			$remainder = substr($Line['text'], $length);

			if (trim($remainder) === '')
			{
				if (isset($matches[2]) or in_array($matches[1], $this->voidElements))
				{
					$Block['closed'] = true;

					$Block['void'] = true;
				}
			}
			else
			{
				if (isset($matches[2]) or in_array($matches[1], $this->voidElements))
				{
					return;
				}

				if (preg_match('/<\/'.$matches[1].'>[ ]*$/i', $remainder))
				{
					$Block['closed'] = true;
				}
			}

			return $Block;
		}
	}

	protected function blockMarkupContinue($Line, array $Block)
	{
		if (isset($Block['closed']))
		{
			return;
		}

		if (preg_match('/^<'.$Block['name'].'(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*>/i', $Line['text'])) # open
		{
			$Block['depth'] ++;
		}

		if (preg_match('/(.*?)<\/'.$Block['name'].'>[ ]*$/i', $Line['text'], $matches)) # close
		{
			if ($Block['depth'] > 0)
			{
				$Block['depth'] --;
			}
			else
			{
				$Block['closed'] = true;
			}
		}

		if (isset($Block['interrupted']))
		{
			$Block['markup'] .= "\n";

			unset($Block['interrupted']);
		}

		$Block['markup'] .= "\n".$Line['body'];

		return $Block;
	}

	#
	# Reference

	protected function blockReference($Line)
	{
		if (preg_match('/^\[(.+?)\]:[ ]*<?(\S+?)>?(?:[ ]+["\'(](.+)["\')])?[ ]*$/', $Line['text'], $matches))
		{
			$id = strtolower($matches[1]);

			$Data = array(
				'url' => $matches[2],
				'title' => null,
			);

			if (isset($matches[3]))
			{
				$Data['title'] = $matches[3];
			}

			$this->DefinitionData['Reference'][$id] = $Data;

			$Block = array(
				'hidden' => true,
			);

			return $Block;
		}
	}

	#
	# Table

	protected function blockTable($Line, array $Block = null)
	{
		if ( ! isset($Block) or isset($Block['type']) or isset($Block['interrupted']))
		{
			return;
		}

		if (strpos($Block['element']['text'], '|') !== false and chop($Line['text'], ' -:|') === '')
		{
			$alignments = array();

			$divider = $Line['text'];

			$divider = trim($divider);
			$divider = trim($divider, '|');

			$dividerCells = explode('|', $divider);

			foreach ($dividerCells as $dividerCell)
			{
				$dividerCell = trim($dividerCell);

				if ($dividerCell === '')
				{
					continue;
				}

				$alignment = null;

				if ($dividerCell[0] === ':')
				{
					$alignment = 'left';
				}

				if (substr($dividerCell, - 1) === ':')
				{
					$alignment = $alignment === 'left' ? 'center' : 'right';
				}

				$alignments []= $alignment;
			}

			# ~

			$HeaderElements = array();

			$header = $Block['element']['text'];

			$header = trim($header);
			$header = trim($header, '|');

			$headerCells = explode('|', $header);

			foreach ($headerCells as $index => $headerCell)
			{
				$headerCell = trim($headerCell);

				$HeaderElement = array(
					'name' => 'th',
					'text' => $headerCell,
					'handler' => 'line',
				);

				if (isset($alignments[$index]))
				{
					$alignment = $alignments[$index];

					$HeaderElement['attributes'] = array(
						// FJ style attribute is evil (do NOT pass SanitizeMarkDown()).
						//'style' => 'text-align: '.$alignment.';',
						'align' => $alignment,
					);
				}

				$HeaderElements []= $HeaderElement;
			}

			# ~

			$Block = array(
				'alignments' => $alignments,
				'identified' => true,
				'element' => array(
					'name' => 'table',
					'handler' => 'elements',
				),
			);

			$Block['element']['text'] []= array(
				'name' => 'thead',
				'handler' => 'elements',
			);

			$Block['element']['text'] []= array(
				'name' => 'tbody',
				'handler' => 'elements',
				'text' => array(),
			);

			$Block['element']['text'][0]['text'] []= array(
				'name' => 'tr',
				'handler' => 'elements',
				'text' => $HeaderElements,
			);

			return $Block;
		}
	}

	protected function blockTableContinue($Line, array $Block)
	{
		if (isset($Block['interrupted']))
		{
			return;
		}

		if ($Line['text'][0] === '|' or strpos($Line['text'], '|'))
		{
			$Elements = array();

			$row = $Line['text'];

			$row = trim($row);
			$row = trim($row, '|');

			preg_match_all('/(?:(\\\\[|])|[^|`]|`[^`]+`|`)+/', $row, $matches);

			foreach ($matches[0] as $index => $cell)
			{
				$cell = trim($cell);

				$Element = array(
					'name' => 'td',
					'handler' => 'line',
					'text' => $cell,
				);

				if (isset($Block['alignments'][$index]))
				{
					$Element['attributes'] = array(
						// FJ style attribute is evil (do NOT pass SanitizeMarkDown()).
						//'style' => 'text-align: '.$Block['alignments'][$index].';',
						'align' => $Block['alignments'][$index],
					);
				}

				$Elements []= $Element;
			}

			$Element = array(
				'name' => 'tr',
				'handler' => 'elements',
				'text' => $Elements,
			);

			$Block['element']['text'][1]['text'] []= $Element;

			return $Block;
		}
	}

	#
	# ~
	#

	protected function paragraph($Line)
	{
		$Block = array(
			'element' => array(
				'name' => 'p',
				'text' => $Line['text'],
				'handler' => 'line',
			),
		);

		return $Block;
	}

	#
	# Inline Elements
	#

	protected $InlineTypes = array(
		'"' => array('SpecialCharacter'),
		'!' => array('Image'),
		'&' => array('SpecialCharacter'),
		'*' => array('Emphasis'),
		':' => array('Url'),
		'<' => array('UrlTag', 'EmailTag', 'Markup', 'SpecialCharacter'),
		'>' => array('SpecialCharacter'),
		'[' => array('Link'),
		'_' => array('Emphasis'),
		'`' => array('Code'),
		'~' => array('Strikethrough'),
		'\\' => array('EscapeSequence'),
	);

	# ~

	protected $inlineMarkerList = '!"*_&[:<>`~\\';

	#
	# ~
	#

	public function line($text, $nonNestables=array())
	{
		$markup = '';

		# $excerpt is based on the first occurrence of a marker

		while ($excerpt = strpbrk($text, $this->inlineMarkerList))
		{
			$marker = $excerpt[0];

			$markerPosition = strpos($text, $marker);

			$Excerpt = array('text' => $excerpt, 'context' => $text);

			foreach ($this->InlineTypes[$marker] as $inlineType)
			{
				# check to see if the current inline type is nestable in the current context

				if ( ! empty($nonNestables) and in_array($inlineType, $nonNestables))
				{
					continue;
				}

				$Inline = $this->{'inline'.$inlineType}($Excerpt);

				if ( ! isset($Inline))
				{
					continue;
				}

				# makes sure that the inline belongs to "our" marker

				if (isset($Inline['position']) and $Inline['position'] > $markerPosition)
				{
					continue;
				}

				# sets a default inline position

				if ( ! isset($Inline['position']))
				{
					$Inline['position'] = $markerPosition;
				}

				# cause the new element to 'inherit' our non nestables

				foreach ($nonNestables as $non_nestable)
				{
					$Inline['element']['nonNestables'][] = $non_nestable;
				}

				# the text that comes before the inline
				$unmarkedText = substr($text, 0, $Inline['position']);

				# compile the unmarked text
				$markup .= $this->unmarkedText($unmarkedText);

				# compile the inline
				$markup .= isset($Inline['markup']) ? $Inline['markup'] : $this->element($Inline['element']);

				# remove the examined text
				$text = substr($text, $Inline['position'] + $Inline['extent']);

				continue 2;
			}

			# the marker does not belong to an inline

			$unmarkedText = substr($text, 0, $markerPosition + 1);

			$markup .= $this->unmarkedText($unmarkedText);

			$text = substr($text, $markerPosition + 1);
		}

		$markup .= $this->unmarkedText($text);

		return $markup;
	}

	#
	# ~
	#

	protected function inlineCode($Excerpt)
	{
		$marker = $Excerpt['text'][0];

		if (preg_match('/^('.$marker.'+)[ ]*(.+?)[ ]*(?<!'.$marker.')\1(?!'.$marker.')/s', $Excerpt['text'], $matches))
		{
			$text = $matches[2];
			$text = preg_replace("/[ ]*\n/", ' ', $text);

			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'code',
					'text' => $text,
				),
			);
		}
	}

	protected function inlineEmailTag($Excerpt)
	{
		if (strpos($Excerpt['text'], '>') !== false and preg_match('/^<((mailto:)?\S+?@\S+?)>/i', $Excerpt['text'], $matches))
		{
			$url = $matches[1];

			if ( ! isset($matches[2]))
			{
				$url = 'mailto:' . $url;
			}

			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'a',
					'text' => $matches[1],
					'attributes' => array(
						'href' => $url,
					),
				),
			);
		}
	}

	protected function inlineEmphasis($Excerpt)
	{
		if ( ! isset($Excerpt['text'][1]))
		{
			return;
		}

		$marker = $Excerpt['text'][0];

		if ($Excerpt['text'][1] === $marker and preg_match($this->StrongRegex[$marker], $Excerpt['text'], $matches))
		{
			$emphasis = 'strong';
		}
		elseif (preg_match($this->EmRegex[$marker], $Excerpt['text'], $matches))
		{
			$emphasis = 'em';
		}
		else
		{
			return;
		}

		return array(
			'extent' => strlen($matches[0]),
			'element' => array(
				'name' => $emphasis,
				'handler' => 'line',
				'text' => $matches[1],
			),
		);
	}

	protected function inlineEscapeSequence($Excerpt)
	{
		if (isset($Excerpt['text'][1]) and in_array($Excerpt['text'][1], $this->specialCharacters))
		{
			return array(
				'markup' => $Excerpt['text'][1],
				'extent' => 2,
			);
		}
	}

	protected function inlineImage($Excerpt)
	{
		if ( ! isset($Excerpt['text'][1]) or $Excerpt['text'][1] !== '[')
		{
			return;
		}

		$Excerpt['text']= substr($Excerpt['text'], 1);

		$Link = $this->inlineLink($Excerpt);

		if ($Link === null)
		{
			return;
		}

		$Inline = array(
			'extent' => $Link['extent'] + 1,
			'element' => array(
				'name' => 'img',
				'attributes' => array(
					'src' => $Link['element']['attributes']['href'],
					'alt' => $Link['element']['text'],
				),
			),
		);

		$Inline['element']['attributes'] += $Link['element']['attributes'];

		unset($Inline['element']['attributes']['href']);

		return $Inline;
	}

	protected function inlineLink($Excerpt)
	{
		$Element = array(
			'name' => 'a',
			'handler' => 'line',
			'nonNestables' => array('Url', 'Link'),
			'text' => null,
			'attributes' => array(
				'href' => null,
				'title' => null,
				// FJ open link in new tab.
				'target' => '_blank',
			),
		);

		$extent = 0;

		$remainder = $Excerpt['text'];

		if (preg_match('/\[((?:[^][]++|(?R))*+)\]/', $remainder, $matches))
		{
			$Element['text'] = $matches[1];

			$extent += strlen($matches[0]);

			$remainder = substr($remainder, $extent);
		}
		else
		{
			return;
		}

		if (preg_match('/^[(]\s*+((?:[^ ()]++|[(][^ )]+[)])++)(?:[ ]+("[^"]*"|\'[^\']*\'))?\s*[)]/', $remainder, $matches))
		{
			$Element['attributes']['href'] = $matches[1];

			if (isset($matches[2]))
			{
				$Element['attributes']['title'] = substr($matches[2], 1, - 1);
			}

			$extent += strlen($matches[0]);
		}
		else
		{
			if (preg_match('/^\s*\[(.*?)\]/', $remainder, $matches))
			{
				$definition = strlen($matches[1]) ? $matches[1] : $Element['text'];
				$definition = strtolower($definition);

				$extent += strlen($matches[0]);
			}
			else
			{
				$definition = strtolower($Element['text']);
			}

			if ( ! isset($this->DefinitionData['Reference'][$definition]))
			{
				return;
			}

			$Definition = $this->DefinitionData['Reference'][$definition];

			$Element['attributes']['href'] = $Definition['url'];
			$Element['attributes']['title'] = $Definition['title'];
		}

		return array(
			'extent' => $extent,
			'element' => $Element,
		);
	}

	protected function inlineMarkup($Excerpt)
	{
		if ($this->markupEscaped or $this->safeMode or strpos($Excerpt['text'], '>') === false)
		{
			return;
		}

		if ($Excerpt['text'][1] === '/' and preg_match('/^<\/\w[\w-]*[ ]*>/s', $Excerpt['text'], $matches))
		{
			return array(
				'markup' => $matches[0],
				'extent' => strlen($matches[0]),
			);
		}

		if ($Excerpt['text'][1] === '!' and preg_match('/^<!---?[^>-](?:-?[^-])*-->/s', $Excerpt['text'], $matches))
		{
			return array(
				'markup' => $matches[0],
				'extent' => strlen($matches[0]),
			);
		}

		if ($Excerpt['text'][1] !== ' ' and preg_match('/^<\w[\w-]*(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*\/?>/s', $Excerpt['text'], $matches))
		{
			return array(
				'markup' => $matches[0],
				'extent' => strlen($matches[0]),
			);
		}
	}

	protected function inlineSpecialCharacter($Excerpt)
	{
		if ($Excerpt['text'][0] === '&' and ! preg_match('/^&#?\w+;/', $Excerpt['text']))
		{
			return array(
				'markup' => '&amp;',
				'extent' => 1,
			);
		}

		$SpecialCharacter = array('>' => 'gt', '<' => 'lt', '"' => 'quot');

		if (isset($SpecialCharacter[$Excerpt['text'][0]]))
		{
			return array(
				'markup' => '&'.$SpecialCharacter[$Excerpt['text'][0]].';',
				'extent' => 1,
			);
		}
	}

	protected function inlineStrikethrough($Excerpt)
	{
		if ( ! isset($Excerpt['text'][1]))
		{
			return;
		}

		if ($Excerpt['text'][1] === '~' and preg_match('/^~~(?=\S)(.+?)(?<=\S)~~/', $Excerpt['text'], $matches))
		{
			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'del',
					'text' => $matches[1],
					'handler' => 'line',
				),
			);
		}
	}

	protected function inlineUrl($Excerpt)
	{
		if ($this->urlsLinked !== true or ! isset($Excerpt['text'][2]) or $Excerpt['text'][2] !== '/')
		{
			return;
		}

		if (preg_match('/\bhttps?:[\/]{2}[^\s<]+\b\/*/ui', $Excerpt['context'], $matches, PREG_OFFSET_CAPTURE))
		{
			$url = $matches[0][0];

			$Inline = array(
				'extent' => strlen($matches[0][0]),
				'position' => $matches[0][1],
				'element' => array(
					'name' => 'a',
					'text' => $url,
					'attributes' => array(
						'href' => $url,
					),
				),
			);

			return $Inline;
		}
	}

	protected function inlineUrlTag($Excerpt)
	{
		if (strpos($Excerpt['text'], '>') !== false and preg_match('/^<(\w+:\/{2}[^ >]+)>/i', $Excerpt['text'], $matches))
		{
			$url = $matches[1];

			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'a',
					'text' => $url,
					'attributes' => array(
						'href' => $url,
					),
				),
			);
		}
	}

	# ~

	protected function unmarkedText($text)
	{
		if ($this->breaksEnabled)
		{
			// FJ remove trailing slash for self closing tags: same as Security->clean_xss()
			//$text = preg_replace('/[ ]*\n/', "<br />\n", $text);
			$text = preg_replace('/[ ]*\n/', "<br>\n", $text);
		}
		else
		{
			// FJ remove trailing slash for self closing tags: same as Security->clean_xss()
			//$text = preg_replace('/(?:[ ][ ]+|[ ]*\\\\)\n/', "<br />\n", $text);
			$text = preg_replace('/(?:[ ][ ]+|[ ]*\\\\)\n/', "<br>\n", $text);
			$text = str_replace(" \n", "\n", $text);
		}

		return $text;
	}

	#
	# Handlers
	#

	protected function element(array $Element)
	{
		if ($this->safeMode)
		{
			$Element = $this->sanitiseElement($Element);
		}

		$markup = '<'.$Element['name'];

		if (isset($Element['attributes']))
		{
			foreach ($Element['attributes'] as $name => $value)
			{
				if ($value === null)
				{
					continue;
				}

				$markup .= ' '.$name.'="'.self::escape($value).'"';
			}
		}

		$permitRawHtml = false;

		if (isset($Element['text']))
		{
			$text = $Element['text'];
		}
		// very strongly consider an alternative if you're writing an
		// extension
		elseif (isset($Element['rawHtml']))
		{
			$text = $Element['rawHtml'];
			$allowRawHtmlInSafeMode = isset($Element['allowRawHtmlInSafeMode']) && $Element['allowRawHtmlInSafeMode'];
			$permitRawHtml = !$this->safeMode || $allowRawHtmlInSafeMode;
		}

		if (isset($text))
		{
			$markup .= '>';

			if (!isset($Element['nonNestables']))
			{
				$Element['nonNestables'] = array();
			}

			if (isset($Element['handler']))
			{
				$markup .= $this->{$Element['handler']}($text, $Element['nonNestables']);
			}
			elseif (!$permitRawHtml)
			{
				$markup .= self::escape($text, true);
			}
			else
			{
				$markup .= $text;
			}

			$markup .= '</'.$Element['name'].'>';
		}
		else
		{
			// FJ remove trailing slash for self closing tags: same as Security->clean_xss()
			//$markup .= ' />';
			$markup .= '>';
		}

		return $markup;
	}

	protected function elements(array $Elements)
	{
		$markup = '';

		foreach ($Elements as $Element)
		{
			$markup .= "\n" . $this->element($Element);
		}

		$markup .= "\n";

		return $markup;
	}

	# ~

	protected function li($lines)
	{
		$markup = $this->lines($lines);

		$trimmedMarkup = trim($markup);

		if ( ! in_array('', $lines) and substr($trimmedMarkup, 0, 3) === '<p>')
		{
			$markup = $trimmedMarkup;
			$markup = substr($markup, 3);

			$position = strpos($markup, "</p>");

			$markup = substr_replace($markup, '', $position, 4);
		}

		return $markup;
	}

	#
	# Deprecated Methods
	#

	function parse($text)
	{
		$markup = $this->text($text);

		return $markup;
	}

	protected function sanitiseElement(array $Element)
	{
		static $goodAttribute = '/^[a-zA-Z0-9][a-zA-Z0-9-_]*+$/';
		static $safeUrlNameToAtt  = array(
			'a'   => 'href',
			'img' => 'src',
		);

		if (isset($safeUrlNameToAtt[$Element['name']]))
		{
			$Element = $this->filterUnsafeUrlInAttribute($Element, $safeUrlNameToAtt[$Element['name']]);
		}

		if ( ! empty($Element['attributes']))
		{
			foreach ($Element['attributes'] as $att => $val)
			{
				# filter out badly parsed attribute
				if ( ! preg_match($goodAttribute, $att))
				{
					unset($Element['attributes'][$att]);
				}
				# dump onevent attribute
				elseif (self::striAtStart($att, 'on'))
				{
					unset($Element['attributes'][$att]);
				}
			}
		}

		return $Element;
	}

	protected function filterUnsafeUrlInAttribute(array $Element, $attribute)
	{
		foreach ($this->safeLinksWhitelist as $scheme)
		{
			if (self::striAtStart($Element['attributes'][$attribute], $scheme))
			{
				return $Element;
			}
		}

		$Element['attributes'][$attribute] = str_replace(':', '%3A', $Element['attributes'][$attribute]);

		return $Element;
	}

	#
	# Static Methods
	#

	protected static function escape($text, $allowQuotes = false)
	{
		return htmlspecialchars($text, $allowQuotes ? ENT_NOQUOTES : ENT_QUOTES, 'UTF-8');
	}

	protected static function striAtStart($string, $needle)
	{
		$len = strlen($needle);

		if ($len > strlen($string))
		{
			return false;
		}
		else
		{
			return strtolower(substr($string, 0, $len)) === strtolower($needle);
		}
	}

	static function instance($name = 'default')
	{
		if (isset(self::$instances[$name]))
		{
			return self::$instances[$name];
		}

		$instance = new static();

		self::$instances[$name] = $instance;

		return $instance;
	}

	private static $instances = array();

	#
	# Fields
	#

	protected $DefinitionData;

	#
	# Read-Only

	protected $specialCharacters = array(
		'\\', '`', '*', '_', '{', '}', '[', ']', '(', ')', '>', '#', '+', '-', '.', '!', '|',
	);

	protected $StrongRegex = array(
		'*' => '/^[*]{2}((?:\\\\\*|[^*]|[*][^*]*[*])+?)[*]{2}(?![*])/s',
		'_' => '/^__((?:\\\\_|[^_]|_[^_]*_)+?)__(?!_)/us',
	);

	protected $EmRegex = array(
		'*' => '/^[*]((?:\\\\\*|[^*]|[*][*][^*]+?[*][*])+?)[*](?![*])/s',
		'_' => '/^_((?:\\\\_|[^_]|__[^_]*__)+?)_(?!_)\b/us',
	);

	protected $regexHtmlAttribute = '[a-zA-Z_:][\w:.-]*(?:\s*=\s*(?:[^"\'=<>`\s]+|"[^"]*"|\'[^\']*\'))?';

	protected $voidElements = array(
		'area', 'base', 'br', 'col', 'command', 'embed', 'hr', 'img', 'input', 'link', 'meta', 'param', 'source',
	);

	protected $textLevelElements = array(
		'a', 'br', 'bdo', 'abbr', 'blink', 'nextid', 'acronym', 'basefont',
		'b', 'em', 'big', 'cite', 'small', 'spacer', 'listing',
		'i', 'rp', 'del', 'code',          'strike', 'marquee',
		'q', 'rt', 'ins', 'font',          'strong',
		's', 'tt', 'kbd', 'mark',
		'u', 'xm', 'sub', 'nobr',
				   'sup', 'ruby',
				   'var', 'span',
				   'wbr', 'time',
	);
}